Production of valuable hydrocarbons



March 27, 1945 L Ll HALL ET AL 2,372,198

PRODUCTION OF VALUABLE HYDROCARBONS 5x5/ear more `March 27, 1945.

E. L. HALL ET AL PRODUCTION OF VALUABLE HYDROCARBONS Filed Jan. 27, 1940 4 s sheets-sheet 2 March 27, 1 945. E. L. HALL E1' AL PRODUCTION OF VALUABLE HYDROCARBONS Filed Jan. 27, 1940 3 Sheets-Sheet I5 Patented Mar. 27, 1945 UNITEDl STATES PATENT OFFICE vALUABLE nimpo- PRODUCTION F lCARB tyun G. Terzian, Philato The United Gas Im- Edwin L. Hau and Ham delphia, Pa., assignors ONS provement Company, a corporation of Pennsylvania Application January 2v, 1940, serial Nn. 315,935

(ci. 26o-671) 2 Claims.

costly portions, such as gas oil and residuum oil, under conditions which yyield relatively large quantities of fixed or diillcultly condensable gases,

such as hydrogen, methane, and ethylene together with other. gaseous paraiiines and oleflnes, and relatively small quantities of more readilyl condensable hydrocarbons comprising tar, drip oil and lower temperature condensates Broadly stated, the division between the gaseous and other products depends upon the severity of cracking and the severity of condensation.

It has been proposed to modify the usual conditions of cracking temperatures and time of contact and the temperature of condensation to produce and recover smaller proportions of the orig# inal oil as gaseous products for distribution as fuel and larger proportions as condensate containing hydrocarbons more valuable for other uses.

Among the hydrocarbons so recoverable are saturated and unsaturated compounds such as benzene, toluene, xylene, naphthalene, anthracene, indene, styrene, methyl styrene, cyclopentadiene, dicyclopentadiene, butadiene, isoprene` piperylene, etc. y

The usual condensation in oil gas manufacture down to atmospheric temperature removes from y the gas practically all of the xylene, naphthalene. anthracene, indene, styrene, and methyl styrene, a small part of the benzene, and possibly half of the toluene. For the recovery of the remainder 0i the benzene and toluene and for the recovery of the dienes much lower temperatures of condensation than usually employed in gas manufacture are required.

Among the aromatic hydrocarbons noted above, the alkylated (including alkylenatem aromatics are in general more valuable than the benzene. This is particularly true of the toluene, xylene and styrene..

An object of the present invention is to provide an improved method of increasing the yield combination of parts, all of which together with` other features willbecome more apparent to persons skilled in the art as the specincation prooeeds and upon reference to the drawings in which: f

Figure l shows in elevation and partly in section, a three shell gas set chosen for illustration;

Figure 2 shows a flow sheet illustrating the invention; and

Figure 3 is an elevation, partly in section, diagrammatically illustrating apparatus of the continuous or continual type.

Referring more particularly to Figure l, I indicates-a generator, 2 a carburetter, 3 a superheater and 4` a wash box. Y n

Generator I is #illustrated as having a fuel burner 5, an uprun air blast supply 6, and an uprun steam supply 1.

'of alim/lated aromatic hydrocarbons relative to superheater 3 is shown with a. downrun steam supply 8.

Generator I is provided at its top with an oitake 9 leading to the top of\the carburetter 2, and carburetter 2 is provided at its base with an off-take I0, leading to the base of the superheater 3. superheater 3 is shown with a stack valve II and a gas off-take I2, the latter leading to wash box 4 through valve I3.

Generator I has a gas off-take I4 at its base provided with valve I5. Gas olf-take I4 leads to wash box 4.

Wash box 4 is shown with the conventional gas off-take I6. o

The apparatus sofar particularly described is illustration in character. Any other gas-making equipment employing a. run with oil might have been substituted for the purposes of describing the invention.

The operation of the apparatus will be described with a cycle, chosen for illustration.

Liquid or gaseous fuel supplied to burner 5 l the generator I, through off-take 9, down through f the carubretter 2 and up through superheater 3, raising. the temperature of the carburetter and vsuperheater and storing heat therein, and iinally escape through-stack valve II or to `a waste heat boiler (not shown) or otherwise.

If desired, secondary air may be introduced at I1 through pipe I8 controlled by valve I9.

The blast is so conducted as to obtain a desired distribution of heat throughout the carburetter and superheater.

After the air blasting operation the set is purged of blast gases by steam admitted at any convenient point, such as at 'I or at 23, whereupon stack valve II is closed, valve Il is opened and a forward run with oil is made during which steam 4is preferably supplied, such as at/l or Supplying steam at I has the eife'ct of causing the steam to `pass up through the generator whereupon it becomes highly superheated before reaching the carburettenthus relieving the car- 2 y buretter from the duty of furnishing this heat.

It will, of course, be understood that a part of the steam maybe admitted at l and a part at 23, thus making it possible to regulate the temperature of the steam entering the top of carburetter 2, or all of the steam may be admitted at l or 23 with any desired degree of preheat. Reference is made to copending application Serial No. 191,441, led February 19, 1938, by Edwin L. Hall.

Although the point of introduction of oil for the forward run may vary in different gas-making equipment, for convenience in description,l

I have illustrated an oil spray 2| at the top of carburetter 2.

Although the point of introduction of oil forr the forward run may vary in different gas-making equipment, for convenience in description, have illustrated an oil spray 2l at the top of carburetter 2.

Irrespective of the construction of the inside of the carburetter, which may vary widely in different types of apparatus, it is customary to have a substantial part of this oil come directly into contact with the heated refractory surfaces, whether they include checkerbrick, or other construction or comprise merely the side walls. However, whether coming into contact with the heated refractory surfaces or not this oil is subjected to the temperatures of the carburetter and superheater, and as it is carried down through the carburetter and up through thev superheater along with the steam it is cracked into gas, coke, tar, drip oil and other condensates.

The coke is usually deposited in the carburetter and superheater and the condensates are usually carried out of the superheater in the vapor phase and are condensed at the wash box and further on in other condensing equipment.

After the forward run, if desired, a back-run might be made as follows. Valve i3 is closed, valve I5 opened and steam is reversed through the set by admitting it at il, While injecting oil into the top of the superheater 3 through any suitable mechanism illustrated generally at 2t. 'Ihis oil is carried down through superheater 3 and up through carburetter 2 and is cracked into hydrogen and hydrocarbons which pass down through generator l with possibly some further pyrolysis and fixing and oi through olf-take I4 directly to the wash box 4.

The desired hydrocarbonsr are condensed at the Wash box and/or recovered further on in condensing or other recovery equipment, as in the previous run.

To complete the cycle the reverse run with steam is followed by a forward purge with steam.

'I'he above is a description of a cycle in carburetted Water gas manufacture chosen-for illustration since a carbonaceous fuel bed might be substituted in the generator I for burner 5. Any other appropriate cycle might be substituted. For instance, the reverse run might be omitted.

After passing through the off-take I6 the gas usually goes through water cooled condensers to a relief holder and from thence to the purifiers for the removal of hydrogen sulde, and thence to storage holders for` release to the distribution system.

The wash box 4 inlwhich the gas comes in contact with Water, and the water cooled condensers cool the gas down to approximately atmospheric temperature. The tar and oil condensed out in these'vessels'comprises a residual tar fraction boiling above 300 C.. a dead oil fraction boiling between 200 C. and 300 C., and a light oil fraction boiling up to 200 C. and containing practically all of the styrene, indene, and xylene, possibly, half or more of the toluene and some of the benzene and other miscellaneous hydrocarbons or benzol forerunnings. The individual compounds may be recovered from the light oil by fractional distillation.

Usual gas practice does not carry the condensation further. However, if after purification oil gas for example, is cooled by stages to approximately 65 C., the remainder of the benzene and toluene as well as the dienes, cyclopentadiene, butadiene, isoprene, and piperylene, may be condensed out and recovered separately by fractional distillation.

Other condensate recovery means may be combined with or substituted for refrigeration, for example, absorption such as in a. scrubbing oil; adsorption, such as on activated carbon, and/or compression.

By resorting Ito recovery by stages, these i materials may be removed from the gas in more paraffineseolenes and dioleiines cyclic olefines and naphthenes aromatics Normally, the production of benzene is relatively high compared to the production of toluene and the higher individual aromatic derivatives such as the xylenes, styrene, indene, etc.

The production of the alkylated aromatics probably proceeds at least in substantial part by union of benzene with free alkyl radicals as benzene-l-free radicals-aalkylated aromatics In the normal course of the reactions through the set or other cracking apparatus, the production of benzene is a delayed reaction occurring in the later stages of the cracking operation. On the other hand, the production of free radicals occurs largely in the initial stages of the cracking operation.

As described and claimed in copending application Serial Number 220,649, filed July 22, 1938 (now Patent Number 2,226,531, dated December 31, 1940) by Newcomb K. Chaney, by increasing the concentration of benzene above that caused by the concurrent formation of benzene in the y oil cracking operation in its early stages, a greater benzene concentration is provided at the time of maximum free radical formation and the above reaction of benzene with free radicals to form alkylated aromatics is favored.

Also the presence of an increased benzene concentration above the normal equilibrium concentration in the later stages of the cracking operation tends to oppose the formation of additional benzene by mass action. This tends to suppress the breaking up of alkylated aromatics formed in the earlier stages to form benzene in the later stages of the cracking operation.

Whether the theory above set forth be correct or not, increasing the benzene concentration above that produced by the normal formation of benzene from the oil in the early stages of the cracking operation favors an increase in the yield of alkylated aromatics relative to the yield of benzene.-

'I'he increased concentration cfbenzene may cyanide are examples.

be secured by introducing additional benzene into the cracking chamber4 during the cracking of the oil. i'

In accordance with this invention, all or part of the benzene may be separated from the products of cracking and recycled through the cracking chamber or chambers by scrubbing benzene from the gas, using the hydrocarbon feed oil to the set as the scrubbing medium. Benzene is thus separated from the gas by absorption in the hydrocarbon oil prior to the admission of the oil into the cracking apparatus, as through supply means 2| or 24 in the drawings. However, as

temperatures in the cracking apparatus, such as the carburetter and superheater above described, may be widely Varied with different cycles and methods of operation, it will be understood that the oil with benzene in admixture may be fed to the set at any other appropriate point or points.

The benzene recycled in this manner need not be a .relatively refined benzene, but may be a crude benzol-containing cut washed from the make gas in the manner described. In fact, a very materially increased yield of styrene, a very valuable alkylated aromatic can be secured by washing from the gas with make oil and recycling a 4light oil cut containing measurable quantities of toluene, xylene, and styrene, in addition to benzene.

It is to be understood that additional benzene over and above that'removed from the gas may, if desired, be added to the hydrocarbon oil prior to its admission to the cracking apparatus and/or such additional benzene may be introduced separately to the same portion or portions of the cracking apparatus or to a different portion or portions.

` which the gas has been In Figure 2, 30 represents a gas set shown dial 4grammaticallyas comprising generator 3l, carburetter 32, superheater 33 and wash box 34 all connected in series.

Gas off-take 36 from the wash box 34 leads to tar condenser 31 which in turn has a gas off-take 33 leading to tar mist extractor 39.

From mist extractor 39 the gas flows through line '40 to relief holder 4I and as shown from re.

p lief holder 4| through line 42 through compressor or booster 43 and line 44 to and through purifier system 45 of any suitable design and then through line 46 into scrubber 41. The compressor or booster 43 may be placed either upstream or downstream from purifier system 45.. In dry purification for example, it is usually placed downstream.

The purier system 45, which may be of the dry purification or liquid purification or other type, serves to. remove from the gas various impurities such as sulfur and cyanogen containing compounds of which hydrogen sulfide and hydrogen Since it is preferred not to build up a high concentration of these materials in the set by recycling, the use of a purifier system upstream from scrubber 41, for example of the type used in ordinary'gas manufacture is recommended.`

On the other hand, since condensation of hydrocarbons is undesirable in purifier systems and particularly in those of the oxide type', as a protection against any considerable condensation of higher boiling hydrocarbons in the purifier system, a part or all of the purification may take place downstream of scrubber 41. A second puriiier system 45a has been illustrated for this purpose, the use of which is optional.

The apparatus described in Figure 2 -up t0 scrubber 41 and its hook-up may be regarded as illustrative and any other suitable apparatus or system or hook-up might be substituted.

An oil supply for the set 30 is illustrated at 48 from which oil flows as through pump 49 and Kline 50 to scrubber 41, wherein oil and gas are contacted by any suitable means known in the art for the purpose of scrubbing higher boiling constituents from the gas. Towers Whether of the packed or bubble plate variety or otherwise are very suitable for the purpose. Other types of scrubbers will be found in the art.

As pointed out previously, there will be a higher percentage of total benzene present in the gas just prior to entering scrubber 41 than of higher boiling light oil constituents, such as toluene, styrene, xylene, etc., although there may be signicant quantities of the latter substances present depending upon the temperature to reduced by the time it reaches scrubber 41.

IAs an illustration, if the gas is reduced to a temperature o'f 95 F. prior to entering scrubber 41, it might have present in it of the order of approximately 1/3 of the total toluene, 80% of the total benzene, from -10 to 30% of the total xylene, and from l0 to 30% of the total styrene. Reference is made to copending application, Serial No.A 301,330, filed October 26, 1939, by Edwin L. Hall.

These materials are washed from the gas in scrubber 41 to an extent dependent upon (l) the eillciency of contact, and (2) the amount of wash oil employed per unit of gas scrubbed.

When the make-gas is substantially all oil gas with no or very little water gas, the rate of feed of oil to the gas set 30 may run as high as l2 to l5 gallons or more of oil per thousand cubic feet of gas. This will of course, vary with the B. t. u. per cubic foot of the gas, or in other words, with the extent to which the oil is cracked to form gas. For instance, the more the oil is cracked, the larger the volume of gas produced per unit of oil, and vice versa.

Assuming that all of the feed oil is contacted with the gas under fairly eilicient contact conditions, and depending somewhat upon the composition of the gas which may vary, this scrubbing step will remove from the gas substantially all .of the remaining styrene, xylene and toluene,-

the preponderate part of the benzene and a part of any hydrocarbons of 5 carbon atoms, such as should it be desired to reduce the ratio of on `to gas in scrubber 41, for instance, to reduce the precentage of C5 hydrocarbons scrubbedout, this might be done by providing a by-pass around scrubber 41 illustrated generally as line 52 which is shown provided with a. valve 53.

Accordingly, it will beseenthat the feed oil may be charged in scrubber 41 with various amounts of benzene as well as other constituents boiling in the neighborhood thereof.

Should it be desired to recover substantially all or a larger proportion of the xylene, styrene entering the set at any desired stituents as condensates.

Other means for regulating the proportion of the various constituents in the gas entering scrubber 41 will become apparent to persons skilled in the art upon becoming familiar herewith.

It will, of course, be understood that scrubber V41 is illustrated diagrammatically and may take any form, shape or construction suitable for the purpose and may comprise one or more units as desired.

While temperature regulating means for scrubber 41 have not been illustrated, it is to be understood that such may be provided, for instance, for a control of the absorbing capacity of the oil. Likewise pressure regulating means may be employed if desired with or without temperature regulating means.

The scrubbed gas, as illustrated, leaves scrubber 41 through line 54 (and puriiier system 45a, if employed) and as shown passes through a condensate recoveryv system 55 from which the residual gas ows off through line 56 such as to a holder, not shown.

'Ihe condensate recovery system 55 may or may not be employed as desired.

For the purpose of such further condensation compression, absorption such as in a scrubbing oil, adsorption such as on activated carbon, andcombinations of the foregoing are available.

In order to provide for the continuous ow kof hydrocarbon scrubbing oil through scrubber 41 as opposed to the intermittent feeding of the charged hydrocarbon oil into the cyclically operated set 30, a surge tank 58 may be provided in line 5|. l,

Relief holder 4| provides for the continuous flow of gas through purifier if used, scrubber 41, purifier 45a if used, and extraction unit 55 as opposed to the intermittent flow of make-gas to relief holder 4| through line 40.

It will be understood, however, that scrubber 41, extraction unit and the purier or purifiers may be operated continually, intermittently, or otherwise if desired, without departing from the broad concept of the invention.

The three shell set and cycle earlier described were given merely for convenient illustration of apparatus adapted for use with my invention, and are subject to very wide modication. If a fuel bed is employed for heating the set, as in carburetted Water gas practice, it may be preferable to curtail sharply or to omit the production of blue water gas, employing the fuel bed merely as a means of heating the carburetter and superheater. In such case, in the absence of the blue Water gas and excess steam cracking atmos# pliere, it is desirable to admit steam or other diluent to the carburetter with the hydrocarbon oil to reduce the partial pressures of the vapors and products of cracking. This steam may be admitted' through a. supply means such as 23. The fuel bed', of course, may be replaced by any other convenient means of heating such as an oil, tar, or gas burner as illustrated at 5 in which case it is also desirable to admit steam or other diluent with the oil. The above modifications are merely illustrative. The invention is applias'zaiosv cable to any process i'n which hydrocarbon oil is thermally cracked under temperature and contact conditions yielding relatively xed gas and more readily condensable hydrocarbons including benzene and alkylated aromatics.

Referring now to Figure 3 wherein cracking apparatus of the continuous or continual type is illustrated on a laboratory scale, 65 comprises a reaction tube which may be any suitable material such as quartz, or any of the materials at present employed in continuous or continual cracking operations.

Tube 65 at its inlet 66 is shown provided with a bale 61 in the form of a cup into which project oil feeding tube 68 and steam feeding tube 69. Feeding tubes 68 and 69 pass through and form a gas-tight iit with a closure member 10 for the inlet end of tube 65.

'lube 65 adjacent its outlet end 1| is provided with a gas delivery side arm 12 and a closure member 13, the latter being sufficiently below side arm 12 to form a Well 14. n

'Iube 65 is also shown provided with an axially arranged tube 15 of small diameter. Tube 15, as shown, projects through closure members 10 and 13 and provides a convenient Way of ar-Y ranging thermocouple junctions for the measure of temperature. Tube 15 may be of any convenient material, such as quartz, or any other material suitable for continuous or continual cracking purposes.

. i Tube 65 may be of any convenient length which is usually correlated with the provisions for feeding steam and for feeding and vaporizing oil in order to make it possible to obtain times of contact within a desired range.

For temperature control purposes, tube 65 is shown surrounded with a heating member 11 in the form of a resistance winding which may be provided with several taps, as illustrated at 18; a cooling coil 19 of tubular construction for the flow of cooling iiuid; and another resistance winding 8D provided with suitable taps, illustrated at 8|.

It will be seen that the provision of a cooling coil 19 between resistanceA windings 11 and 80. and the provision of taps 18 and 8| on windings 11 and 80 respectively, make it possible to closely control temperature conditions within tube 65 as well as to vary such conditions along tube 65, if and as desired.

Assuming that heaters 11 and 80 and cooler 19, if necessary, are operating to establish desired temperature conditions within tube 65, the operation of the apparatus shown in Figure 3 is as follows:

Oil is fed in through tube 68 and steam through tube 69. Both oil and steam strike baille 61, thus becoming mixed. I'he resulting'reduction in partial pressures of oil vapors and the surrounding temperatures are ordinarily suflicient Vto vaporize all of the oil.

'I'he vaporized oil in passing through tube 55 is decomposed in a manner similar to that already described in connection with Figure 1.

'I'he resin-forming hydrocarbons along with saturated aromatics, such as benzene, toluene, xylene, etc., because of the temperatures involved remain in the vapor phase and pass off through the gas.

lustrative of those obtaining in tube 65, although any other desired temperature or temperatures suitable for the purpose may be employed.

Times of contact of from 0.5 to 3 seconds are illustrative, although any other desired time of v are eliminated, delivery arm 12 is connected to gas oil-take `36, and line is connected to oil feed tube 68, whereupon elements 36 to 56 are made to function in all respects similar to that already described in connection with Figure 2.

The apparatus of Figure 3 is of course largely for illustration and may be replaced by a plant size unit or units. A i

If desired, tube 65 may contain refractory material of suitable size and shape if suillcient free space is afforded for the flowof vapors, such additional refractory materials providing additional contact surfaces.

Also any other heating means may be added or substituted. l

.Small amounts of free carbon or other nonvaporizable substances tend to collect in well 64 from which they may be removed during cleaning upon the removal of closure member 63.

When the walls of tube 65 become coated with a layer of carbon suciently thick to interfere with proper heat exchange, or otherwise, it may beremoved by any suitable means such as by introducing air or oxygen through tube 68 or 69 or both, the products of combustion being removed through side arm 12.

Any desired proportion of steam to oil may be employed in our process of which two volumes of steam to one volume of oil vapors is illustrative.

As an example of increased yields of valuable alkylated aromatic hydrocarbons in the laboratory apparatus of Figure 3, the following may be given.

A mixture of particular crude oil and benzoll 'in proportions of 2 parts oil and 1 part benzol by volume was cracked under substantially similar conditions of tempera/ture and contact as a control employing 100% of the same crude oil, in a quartz contact tube known commercially as Vitrosil.-

The inside diameter of the tube was 1% inches and the length 35.4 inches.

In each case steam was admitted with the material cracked. The table below shows the increased yields of certain valuable alkylated aromatic hydrocarbons especially styrene when employing oil and benzol, the term alkylated being usedy herein to include unsaturated as well as saturated hydrocarbon side chains.

Table I f Two arts by vo umev crude oil- 100% crude one part by oil volume benzol Liza/aal: all Lbalaal. oil

There was also produced in the case of the mixed oil and benzol 0.301 pound per gallon of oil formance of our invention than those set forth above will occur to those skilled in the art upon becoming familiar herewith.

For instance, pyrolysis may be supplemented by other means for decomposing the oil of which catalysis is an example. Thus a combination of temperature and catalyst is within the purview of the invention. I

The term hydrocarbon oil" as used herein embraces petroleum oil whether in the form of the crude vor any fraction thereof suitable for gas-making purposes.

Therefore, changes, omissions, additions, substitutions and/or modiiications may be made within lthe scope of the claims without departing from the spirit of the invention. Y

We claim:

l. I n the manufacture of combustible gas involving the vapor phase pyrolysis ofpetroleum oil in a heatedpetroleum oil pyrolyzing environment and in an atmosphere of added benzene contained therein with the production 0i. gaseous hydrocarbon products of pyrolysis comprising benzene and saturated and unsaturated hydrocarbon material boiling higher and lower than benzene including hydrocarbon material boiling in the neighborhood of the boiling point of benzene; the steps of removing from said gaseous products of pyrolysis at least a substantial por- -leaving a residual gas rich in hydrocarbon maoerial boiling lower than benzene; and introducing said petroleum oil so enriched with benzene and similarly boiling hydrocarbon material into said heated petroleum oil pyrolyzing environment for pyrolysis therein.l

2. In a cyclic combustible gas manufacturing process in which heat is stored in a petroleum oil pyrolyzing zone during a heating portion of the cycle and in which the stored heat is utilized during ay petroleum oil pyrolyzing portion of the cycle for the vapor phase pyrolysis of petroleum oil in the presence of added benzene with the production of gaseous hydrocarbon material including benzene and hydrocarbon material having boiling points higher and lower than the boiling point of benzene including hydrocarbon material of similar boiling point to benzene; 4the of dienes while in the case of the oil, there was produced 0.355 pound per gallon of oil of dienes comprising in each case butadiene, cyclopentadiene and dimer. isoprene and piperylene.

Qther modificationsv in procedure in the persteps of removing from the gaseous products of said pyrolysis at least a substantial portion of said hydrocarbon materia1 boiling higher than benzene; thereafter contacting the remaining gaseous products of said pyrolysis with a scrubbing medium comprising petroleum oil to abs'orb benzene and hydrocarbon material of similar boiling point to benzene from said remaining gaseous products of pyrolysis, thereby obtaining a residual gas rich in hydrocarbon material boiling lower than benzene and petroleum oil .enriched with benzene and hydrocarbon material of boiling point similar to benzene, and introducing said petroleum oil containing said absorbed benzene and hydrocarbon material of similar boiling point to benzene into said heated petroleum oil pyrolyzing zone during the oil pyrolyzing 1 portion of said cycle for pyrolysis therein. 

